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Tight junction protein abundance is altered in Metformin treated airway epithelial cells
Author(s) -
Kalsi Kameljit K,
Garnett James P,
Baker Emma H,
Baines Deborah L
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.968.4
Subject(s) - occludin , metformin , tight junction , staphylococcus aureus , chemistry , medicine , endocrinology , biology , diabetes mellitus , biochemistry , bacteria , genetics
Airway epithelial tight junction (TJ) proteins form a resistive barrier to the external environment, however during respiratory bacterial infection TJ abundance is altered. Metformin used for the treatment of diabetes is known to increase transepithelial resistance (TEER) of airway epithelial cells. We investigated the effect of metformin and Staphylococcus aureus inoculation on TJ abundance and the assembly/reassembly of the TJ protein in airway epithelial cells. Occludin protein was detected by immunoblot analysis with a major protein band at 60 kD with cleavage products at 46, 44 and 37 kD in human airway epithelial cells (H441), pre‐treatment with 1 mM metformin for 18h, resulted in an increase in the 60 kD protein band (13 ± 7%, P <0.05; n=4) and a decrease in the cleavage product at 44 kD (37 ± 4%, P <0.05; n=4). Inoculating H441 monolayers with S.aureus produced a significant reduction in abundance in both 60 and 44 kD protein bands (35 ± 11% and 41 ± 5% respectively, P <0.05; n=4) which was not reversed with metformin pre‐treatment. Similarly occludin and Z0‐1 abundance were both enhanced with metformin and reduced with S.aureus in immunostained epithelial monolayers. Disassembly and reassembly of TJs in the presence of a calcium chelating agent was not protected or enhanced by metformin pre‐treatment. These data provide evidence that metformin regulates TJ protein abundance through a mechanism that does not involve changes in assembly. Support or Funding Information MRC‐MICA MR/K012770/1